1. Field of the Invention
The present invention relates to a metal coating treatment for strengthening the surface of a workpiece, improving the lubrication, wear resistance, heat resistance and anti-corrosion of the surface, decorating the surface, or the like, and more specifically to a ceramic dispersion plating process of dispersing ceramic particles into the surface of a workpiece and ejecting a metal powder to form a metal coat.
2. Description of Prior Art
Hitherto, there have been known hot-dip plating, electroplating, electroless plating, other vacuum evaporation, thermal spray and the like processes, as metal coating processes.
There has also known a composite plating process of incorporating ceramic particles (inorganic material particles) into a metal coat in order to make higher the strength, lubrication, wear resistance, heat resistance, adhesion or the like of the surface of a workpiece.
For example, the hot-dip plating process is a plating process of immersing a workpiece into a melted metal bath and subsequently raising the workpiece from the metal bath after a given time, and is carried out by using metals having a relatively low melting point. This process includes hot-dip zinc plating, hot-dip tin plating, hot-dip aluminum plating, hot-dip lead plating and the like.
The composite plating process is a manner of floating particles of alumina, silicic anhydride, silicon carbide or the like into a plating bath in an electroplating or electroless plating process and then embedding the particles into a metal deposited onto the cathode so as to incorporate/mix the particles into a resultant electroplating metal coat or electroless plating metal coat. This process is applied to a sliding member or the like.
The conventional metal coating treatments have the following problems.
(1) In, for example, the hot-dip plating process a liquid melted metal into which a workpiece of a solid metal is immersed is necessary. Therefore, costs of heating facilities are high for keeping the liquid metal constantly in a melted state.
There also arises a problem that the cost of this process is high since the rate of inferior products is high because of a lack of adhesion. For example, in the plating of an iron cast with chromium and the plating of an aluminum die casting product with melted nickel the inferior rate thereof is high because of a lack of adhesion. Thus, stable plating cannot be carried out.
(2) In the conventional metal coating treatments, harmful chemicals are used so that it is feared that pollution occurs, such as environment pollution caused by harmful vapor generated at the time of the metal coating treatment.
(3) In the composite plating, the costs of facilities are high, and additionally it is feared that pollution occurs for the same reason as in the aforementioned item (2).
Moreover, inorganic material particles are incorporated into a plating layer, and thus the plating layer becomes thick. Thus, exfoliation resistance strength is required and further post-processing becomes difficult.
In the case wherein the composite plating is applied to a sliding area, a companion member may be worn away by ceramic particles.
(4) When a plating layer is exfoliated in the conventional metal coating treatments, effects of the plating cannot be obtained.
The present invention has been made to solve the aforementioned problems, and thus it is an object to provide a low-priced metal coating treatment which causes less pollution by carrying out the dispersion of ceramics and the forming of a metal coat by blasting treatment, and provide a ceramic dispersion plating process wherein a lubrication face is formed on the surface of a workpiece so as to make it possible to improve its wear resistance, heat resistance and anti-corrosion, and decrease or overcome plating inferiority.